Carbohydrates can be converted into other materials by bioprocessing techniques that utilize agents such as microorganisms or enzymes. For example, in fermentation carbohydrates are converted into alcohols or acids by microorganisms, e.g., sugar is converted to alcohol using yeast under anaerobic conditions. When fermentation stops prior to complete conversion of a carbohydrate to a product, e.g., sugar to alcohol, a “stuck” fermentation is said to have occurred.
Other bioprocessing techniques include the enzymatic hydrolysis of cellulosic and lignocellulosic materials into low molecular weight sugars.